Sonar utilizes sound waves which are transmitted through the water. The sonar equipment receives sound signals from the water; amplifies the signals; and analyzes the signals so that the sonar operator will receive information about objects and their movements in the sea. Sonar systems receive sound energy from hydrophones. Hydrophones are used to convert sound energy into electrical signals. The electrical signals are then processed and displayed to a sonar operator who is typically aboard a ship or aircraft. The ability of a sonar operator to find or locate a target is dependent upon how faint a sound the hydrophone can detect and the ability of the sonar equipment to determine the location of the object that produced the detected sound.
One method utilized by the prior art to increase the range of hydrophones was to deploy an array of omni-directional hydrophones in a substantially horizontal straight line array beneath the ocean's surface (the sound detection power of the hydrophones increases by the .sqroot.N, where N equals the number of hydrophones). One of the disadvantages of deploying omnidirectional hydrophones in a substantially straight line is that it does not permit the operator to determine which lobe (left or right) of the symmetric beam contains the target.
Another method utilized in the prior art for increasing the range and direction sensitivity of an array of hydrophones involved a mechanical structure containing rigid radial arms upon which are supported or suspended a symmetrical planar array of hydrophones. A disadvantage of positioning hydrophones with a rigid mechanical structure is that when such mechanical structures move through water, the joints of the mechanical structure flex when water passes them. The foregoing flexing produces background noises which interfere with the operation of the hydrophones. Another disadvantage of such mechanical structures is that usually the hydrophones could only be affixed to the radial arms of the structure and it was not practical to build a mechanical structure with more than about six radial arms. Thus, the hydrophones on different radial arms were positioned at least 60.degree. apart which is acoustically disadvantageous as it limits the number of hydrophones which may be effectively employed. Furthermore, the radial arms were large, heavy and bulky, as they had to be both rigid when extended and yet capable of being collapsed so that the mechanical structure and hydrophones could be stored in a package of manageable size before the hydrophones were deployed. Mechanically structured arrays were also difficult to deploy, and costly since they were complex and difficult to fabricate.